Separation And Functional Identification Of Soybean Peptides

Soybean physiologically active peptide is the mixture of soy peptides and amino acids which obtained from hydrolysis of soybean protein. In certain molecular weight scope, it is as same as the soy protein in amino acids constituted. Compared to the characteristic of soy protein that limits the practical application of production, such as a low solubility, a certain antigen, and a low digestibility and biological effects, the soybean peptide has obvious advantages. It is easy to be digested, and has a variety of physiological functions, such as oxidation resistance, lower blood pressure, lower cholesterol and prevent osteoporosis, etc. It can be used as functional ingredients in dairy, beverage, candy and other food system.In this study, the original production process about low molecular weight soybean peptide of our laboratory had been optimized, and the necessary mixture of peptide molecular weight had been obtained which was separated by ultrafiltration. And then the soybean peptide had been studied on the activity of anti-tumor, lipid-lowering, antioxidant, and anti-fatigue, to provide a theoretical basis for further research, and also to provide evidence of the development capabilities of their nutrition and health care. Results were as follow:1. The antioxidant activity of soybean peptide was studied. The gel filtration experiments had been done through Sephadex G-25, collected three peaks, and analyzed the molecular weight range by comparing to the Tricine-SDS-PAGE chromatogram. The results showed that the antioxidant activity of the same concentration soybean peptide increased with the molecular weight decreasing in a certain molecular weight range. Using the method of pyrogallol autoxidation, the rate of change about low molecular weight peptide autoxidation was less than the rate about the blank control group by 52.28%.2. The hypolipidemic and weight loss activity of soybean peptide was studied. The results indicated that, the low dosage of soybean peptide had the best effect of lipid-lowering and weight loss. With the soybean peptide dosage increasing within a certain range, weight loss and lipid-lowering effect would be positive correlation. In this study, the samples of soybean peptide was prepared by new fermentation process using the method of combining microbial fermentation and enzymatic, so that the molecular weight of 77.8% products distribute in the 538-2659Da range. The low dosage concentration got the maximum effect of soybean peptide, and the effect would be reduced with the dosage increasing, because of excessive intake of nutrients. Since bacteria and fungi produced many kinds of protease, and soy protein was also hydrolyzed into many types of low-peptide mixture. The product was a complex of multiple functional peptides, and had a lipid-lowering and weight loss activity which was the combined effects of multiple functional peptides. According to the characteristics of soybean peptide feeding, there must be lipid-lowering and weight loss activity peptides in the soybean peptides molecular weight less than 8KDa.3. The anti-tumor activity of soybean peptide was studied. The results indicated that, the soybean peptide obtained by new process contained the anti-tumor polypeptide composition. Both the fed group and the injected group could play the role of anti-tumor function in a certain concentration, and compared to the negative control group, both of them could have some differences. Relative to the negative control group, the injected group played better. And in the fed group, the low dosage group played best. It could be deduced, there was some peptides with anti-tumor activity in the soybean peptides molecular weight less than 8KDa.4. The anti-fatigue activity of soybean peptide was studied. The results indicated that, the soybean peptide obtained by new process could significantly extend the swimming time of mice loaded weight, and also significantly increase the amount of mouse liver glycogen reserves, as well as the reducing rate of blood lactate of the swimming mice. So the soybean peptide from new production process could obviously relieve fatigue of mice, and the best concentration was 600 mg/kg.bw which is the high dosage.